(a) Field of the Invention
The invention relates to a novel knee laxity evaluator (KLE) system.
The invention also relates to a motion module/digitizer combination which can be used in the KLE, or which can be used independently or in other systems. More specifically, the invention relates to such a combination which can measure, in three dimensional space, and relative to the position of a first point or body or co-ordinate system, position or motion of a second point or body, as well as position or motion of the second point or body relative to a third, fourth, fifth . . . nth points, or positions of the second body, or combinations thereof.
(b) Description of Prior Art
Currently, the practice of measuring knee laxity is limited to a subjective evaluation by a physician of relative displacements at the knee. Through such an examination, damage to ligaments could be ascertained as a function of excess laxity or joint movement during passive loading by the physician. The limitations of this technique are: (a) a high level of subjectivity; (b) no quantitative or reproducible results; (c) no knowledge of applied forces; and (d) there are complicated motions which cannot be evaluated by human feel alone and hence there is important information being lost.
In accordance with the present invention, a KLE includes a motion module, that is, a module for measuring, in three dimensional space, movement of a point or body relative to a fixed point or body. Modules of this type are known in the art as is illustrated, for example, in U.S. Pat. No. 3,944,798, Eaton, Mar. 16, 1976, U.S. Pat. No. 4,057,806, Furnadjiev et al, Nov. 8, 1977, and U.S. Pat. No. 4,205,308, Haley et al, May 27, 1980.
Electrical and electronic digitizers are also known in the art. For example, a two dimensional digitizer is illustrated in U.S. Pat. No. 3,956,588, Whetstone et at, May 11, 1976.
However, there are no teachings in the art for combining the first systems, usually referred to as motion modules, and digitizers, whereby it is possible to measure the position or motion of a second point or body relative to the position of a first point or body and also relative to third, fourth, fifth . . . nth points or positions of the second body or combinations thereof.